text: import unittest
  from translator import english_to_french, french_to_english
  class TestTranslator(unittest.TestCase):
      def test_en_to_fr(self):
          self.assertEqual(english_to_french('Hello'), 'Bonjour')
  
      def test_fr_to_en(self):
          self.assertEqual(french_to_english('Bonjour'), 'Hello')
  
      def test_enfr_null(self):
          self.assertEqual(None,english_to_french(None))
  
      def test_fren_null(self):
          self.assertEqual(None,french_to_english(None))
  if __name__ == '__main__':
      unittest.main()
  